Orbital’s Antares closing in on debut launch following pad arrival

October 1, 2012 by Chris Bergin and Ron Smith

Antares, the launch vehicle tasked with lofting the Cygnus spacecraft on missions to the International Space Station (ISS), finally arrived at its Wallops launch pad on Monday. The arrival of the rocket – ahead of a hot fire at the pad – should mark the end of delays related to construction difficulties for the Mid-Atlantic Regional Spaceport (MARS).

That debut launch – which will be without Cygnus – is still expected before the end of the year, to be followed by Cygnus’ first flight to the ISS to take place early in 2013. Should these demonstrations prove to be successful, Orbital will begin to satisfy their CRS mission obligations.

The main engine for the first stage of the Antares is the Aerojet produced AJ-26.

The engines are rebuilt version of Soviet NK-33, originally intended for the massive N-1 launch vehicle. Aerojet later bought the engines which had never been used and added modern electronics and other performance enhancements.

The tanking for the Antares was contracted to the Yuzhnoye Design Bureau from the Ukraine. Yuzhnoye has extensive knowledge in producing kerosene rocket bodies as the producer of the Zenit launch vehicle.

Orbital Sciences originally conceived of a core with a single NK-33 derived engine combined with strap-on solid boosters. However a second engine was ultimately added to the core and the boosters were removed from the final design.

The second stage of the Antares comes from another industry veteran, Alliant Techsystems (ATK). The vehicle utilizes a solid upper stage called the Castor 30, which is a derivative of the Athena and Taurus I first stage Castor 120 which is in turn a derivative of the Peacekeeper ICBM first stage.

The first two initial flights will use the Castor 30A, while an upgraded version will be utilized for the next two flights called the Castor 30B.

Orbital originally intended at this point to switch to a liquid upper stage called the HESS utilizing the Russian RD-0124. However, the company later decided to go with a stretch of the original upper stage called the Castor 30XL. The Castor 30XL will power the last six flights scheduled right now for the Antares, and will launch extra cargo on a larger Cygnus Spacecraft.

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Two optional third stages are also available for Antares, namely the Hydrazine Propulsion System (HAPS) – a derivative of the Orbital STAR bus designed to inject a payload to a designated orbit with more precision, while the Star 48 third stage can be utilized for orbits requiring higher energy. Neither stage is current slated on the vehicle’s manifest.

Antares will utilize a three digit designation based on the combination of stages utilized. The first digit will always be a one and refer to the kerosene core. The second stage will be labeled 1 for the Castor 30A, 2 for B, and 3 for XL. The last digit refers to the upper stage being utilized, with a 1 being the designation for the HAPS stage and 2 for the Star 48 and 0 for no upper stage.

With the official authorization for Orbital to begin on-pad operations, leading up to flight demonstrations of its Antares vehicle, the first rocket took its historic roll to the pad early on Monday.

“MARS has completed construction and testing operations on its launch complex at Wallops Island, the first all-new large-scale liquid-fuel launch site to be built in the U.S. in decades,” said David W. Thompson, Orbital’s President and Chief Executive Officer, in a statement to the media on Monday.

In the coming weeks, Antares will be put through the major ground test objective of the first-stage hold-down evaluations. For this test, the vehicle’s AJ-26 engines will be ignited for a 30 second hot fire.

“Our pad operations are commencing immediately in preparation for an important series of ground and flight tests of our Antares medium-class launch vehicle over the next few months,” added Mr Thompson.

Once Orbital have demonstrated the readiness of the rocket’s first stage and launch pad fueling systems to support the upcoming flights, Antares will begin a flow lasting around one month ahead of its maiden flight.

For the debut mission, Antares will carry a Cygnus mass simulator payload that will be heavily instrumented to gather data on the launch environment aboard Antares. In addition, four small “pico satellites” will be deployed from two dispensers that will be integrated with the mass simulator.